Study author Dr Sarah Beale, from University College London, said: "Good hand hygiene should be practised at all times regardless of whether you show symptoms or not.

"This will help protect yourself and prevent unwittingly spreading the virus to others around you."

A Public Health England official said: "Regular hand-washing for at least 20 seconds is one of the best ways of stopping the spread of coronavirus, particularly after you blow your nose, sneeze or cough, as well as before eating or cooking.

"Also, it's a good idea to get into the habit after you've been out in public places or on transport."